How do you prevent anxiety attacks?

It depends: The "how" depends on the severity of the anxiety attacks. Many can calm down with deep breathing, inner visualization of a safe, beautiful place. You can practice these skills before the attack. Keeping fit and well rested are helpful too. Consistent meditation. Psychotherapy directed to your specific anxieties. Psychiatric medicines like effexor, (venlafaxine) lexapro, celexa, and zoloft. Some others too.